ES2680923T3 - Air conditioning - Google Patents

Abstract

Air conditioning apparatus (1) comprising: n refrigerant circuit (10) that is configured by connecting a compressor (21), a radiator (23, 41), an upstream side expansion valve (24, 26), a receiver (25), a downstream side expansion valve (26, 24) and an evaporator (41, 23), and in which refrigerant may circulate in the order of the compressor, the radiator, the expansion valve upstream side, the receiver, the downstream side expansion valve and the evaporator, further comprising a control section (8) comprising a suction humidification control section (81) of downstream side configured to perform a downstream expansion valve suction humidification control, an upstream side expansion valve subcooling control section (82) configured to perform an expansion expansion valve subcooling control of side to guides above and a gas exhaust control section (83) configured to perform a gas exhaust control, in which R32 is contained in the refrigerant circuit as the refrigerant, the refrigerant circuit is provided with a pipe (30 ) receiver gas exhaust which is to conduct gaseous refrigerant that accumulates inside the receiver to the suction side of the compressor and which has a receiver gas exhaust valve (30a) that is capable of being controlled to open and closed, the gas exhaust control (83) is configured to be carried out so that the gaseous refrigerant is conducted from the receiver (25) to the suction side of the compressor (21) via the gas exhaust pipe (30) of receiver by opening the receiver gas exhaust valve (30a), the upstream side expansion valve subcooling control (82) is configured to be performed so that an opening of the valve opening (24, 26) is changed. former upstream side housing so that a coolant undercooling is set to a target subcooling at the radiator outlet, and the downstream side expansion valve suction humidification control (81) is configured to be performed so that it changes an opening of the downstream expansion valve (24, 26) so that the refrigerant is in a humidifying state and a dryness is established at an objective dryness at the evaporator outlet, characterized in that the control (81) Suction humidification of downstream side expansion valve is a control in which the opening of the downstream side expansion valve (24, 26) is changed so that a coolant temperature that is discharged from the compressor (21) at an objective discharge temperature that is equivalent to a case in which the dryness of the refrigerant at the evaporator outlet (41, 23) is set to the objective dryness, the upstream side expansion valve subcooling control (82) is configured to be performed with respect to the upstream side expansion valve (24, 26) and the valve suction humidification control (81) downstream side expansion is configured to be performed while a discharge temperature protection control is configured to be performed with respect to the downstream side expansion valve (26, 24) so that a designated correction opening is added at a lower limit opening which is a lower control limit of the downstream side expansion valve (24,26) in the case of satisfying a discharge temperature protection condition, which is determined when the coolant temperature that Discharged from the compressor (21) increases to a protective discharge temperature that is greater than the target discharge temperature or when the quantity is The state that correlates with the temperature of the refrigerant that is discharged from the compressor (21) reaches an amount of protection status corresponding to the protective discharge temperature.

Description

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DESCRIPTION

Air conditioning Technical field

The present invention relates to an air conditioning apparatus and, in particular, relates to an air conditioning apparatus having a refrigerant circuit that is configured by connecting a compressor, a radiator, an upstream side expansion valve , a receiver, a downstream expansion valve and an evaporator and in which it is possible to circulate refrigerant in the order of the compressor, the radiator, the upstream side expansion valve, the receiver, the expansion valve of downstream side and evaporator.

Prior art

In the prior art, there is an air conditioning apparatus having a refrigerant circuit in which expansion valves are provided on the upstream and downstream side of a receiver and gaseous refrigerant is injected from the receiver into a compressor, as shown in PTL 1 (Japanese Unexamined Patent Application Publication No. H10-132393). In detail, the air conditioning apparatus has the refrigerant circuit that is configured by connecting the compressor, a radiator, an upstream side expansion valve, the receiver, a downstream side expansion valve and an evaporator. In the refrigerant circuit an injection circuit is provided that injects intermediate pressure gaseous refrigerant from the receiver into the compressor. Then, in the air conditioning apparatus, an operation is performed in which refrigerant is circulated in the order of the compressor, the radiator, the upstream side expansion valve, the receiver, the downstream side expansion valve and the evaporator and intermediate pressure gaseous refrigerant is injected from the receiver into the compressor.

In addition, there is an air conditioning apparatus that uses R32 as a refrigerant, as shown in PTL 2 (Japanese Patent Application Publication No. 2001-194015). In detail, the air conditioning apparatus has a refrigerant circuit that is configured by connecting a compressor, a radiator, an expansion valve and an evaporator. Then, in the air conditioning apparatus, there is suction humidification control in which the number of rotations of the compressor and / or the opening of the expansion valve is changed so that the refrigerant at the outlet of the evaporator is in a Humidification status designated when performing the operation in which refrigerant is circulated in the order of the compressor, the radiator, the expansion valve and the evaporator.

PTL 3 (JP 2001 241780 A) and PTL 4 (EP 0 685 692 A2) are additional prior art.

JP 2001 241780 A discloses an air conditioning apparatus according to the preamble of claim 1.

Summary of the invention

According to the prior art air conditioning apparatus described above, it is considered that, for example, R32 is used as a refrigerant as in PTL 2 in the air conditioning apparatus having the refrigerant circuit in which the expansion valves they are provided on the upstream side and the downstream side of the receiver and gaseous refrigerant is injected from the receiver into the compressor as in PTL 1. In this case, in the case where R32 is used as a refrigerant, it is necessary to perform a suction humidification control taking into account that it is easy for the temperature of the refrigerant discharged from the compressor to increase as in PTL 2.

However, although the refrigerant circuit having an expansion valve without having a receiver, a refrigerant circuit is described, in which the expansion valves are provided on the upstream side and the downstream side of the receiver and injected gaseous refrigerant from the receiver to the inside of the compressor, is not described in PTL 2. For this reason, there is a problem in how a control that includes the suction humidification control in the refrigerant circuit in which the valves of expansion are provided on the upstream side and the downstream side of the receiver and gaseous refrigerant is injected from the receiver into the compressor as in PTL 1. In addition, there is concern that an increase in the temperature of the refrigerant that is generated discharge from the compressor, as described above when the compressor sucks coolant in which the dryness is greater than the humidification state Designated and that liquid compression is generated when the compressor sucks refrigerant in which the dryness is less than the designated humidification state. For this reason, high control capacity is required with respect to suction humidification control from the point of view of guaranteeing the reliability of the compressor. In addition, an accumulator is provided on the suction side of the compressor in PTL 1 and 2, but since it is difficult for refrigerant to be sucked into the compressor in a humidifying state using the gas and liquid separation function of the accumulator in the In the case where the accumulator is provided in this way, it is said that providing the accumulator on the suction side of the compressor is not preferable in the case in which the control of the

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suction humidification. However, since not providing the accumulator on the suction side of the compressor is a growing concern that liquid compression is generated, it is necessary that the control capability of the suction humidification control be further improved so that the compressor does not Suction coolant in which the dryness is less than the designated humidification state.

In this way, a high control capacity is required in the control of suction humidification from the point of view of guaranteeing the reliability of the compressor, it being necessary for it to perform suction humidification control in the case where R32 is used as refrigerant in the air conditioning apparatus having the refrigerant circuit in which the expansion valves are provided on the upstream side and the downstream side of the receiver and gaseous refrigerant is injected from the receiver into the compressor.

The problem of the present invention is that it is possible to perform a suction humidification control with high control capacity using R32 as a refrigerant in an air conditioning apparatus having a refrigerant circuit in which expansion valves are provided on the side upstream and downstream side of a receiver and gaseous refrigerant is injected from the receiver into a compressor.

According to the present invention, the foregoing objective is solved by the features according to claim 1.

An air conditioning apparatus, according to a first aspect, is an air conditioning apparatus having a refrigerant circuit that is configured by connecting a compressor, a radiator, an upstream side expansion valve, a receiver, an air conditioning valve. downstream side expansion and an evaporator and in which it is possible for the refrigerant to circulate in the order of the compressor, the radiator, the upstream side expansion valve, the receiver, the downstream side expansion valve and the evaporator . R32 is contained in the refrigerant circuit as a refrigerant. In addition, the refrigerant circuit is provided with a receiver gas exhaust pipe that is to conduct gaseous refrigerant that accumulates inside the receiver to the suction side of the compressor and that has a receiver gas exhaust valve that It is able to control itself to open and close. Then, in this case, a gas leak control is performed so that the gaseous refrigerant is conducted from the receiver to the suction side of the compressor via the receiver gas exhaust pipe by opening the receiver gas exhaust valve , an upstream side expansion valve subcooling control is performed, so that an opening of the upstream side expansion valve is changed so that a coolant subcooling is set to an objective subcooling at the radiator outlet , and a downstream side expansion valve suction humidification control is performed, so that the opening of the downstream side expansion valve is changed so that the refrigerant is in a humidifying state and a dryness to an objective dryness at the evaporator outlet.

In this case, due to the presence of the refrigerant circuit in which the expansion valves are provided on the upstream side and the downstream side of the receiver and the gaseous refrigerant is injected from the receiver into the compressor, it is preferable that the device is controlled so that it is possible to directly control the flow rate of the refrigerant flowing into the evaporator in the suction humidification control.

Therefore, in this case, the refrigerant is in a humidification state and the dryness is set to the target dryness at the evaporator outlet by performing the downstream side expansion valve suction humidification control in which the opening of The downstream side expansion valve, which is provided on the downstream side of the receiver, is changed as described above.

However, at this point, it is preferable that the refrigerant sent from the receiver to the downstream side expansion valve is normally maintained in the state of the liquid refrigerant so that the control capacity of the water side expansion valve Below is appropriate. Then, it is necessary to stabilize the flow rates of the gaseous refrigerant and the liquid refrigerant flowing into the receiver, that the gaseous refrigerant does not flow from the receiver into the downstream side expansion valve, and that the refrigerant liquid does not return from the receiver gas exhaust pipe to the suction side of the compressor so that the refrigerant that is sent from the receiver to the downstream side expansion valve is normally kept in the state of the liquid refrigerant.

Therefore, in this case, when performing the humidification control of the downstream expansion valve suction, the gaseous refrigerant is conducted from the receiver to the compressor suction side by means of the receiver gas exhaust pipe that is provides in the receiver performing the gas exhaust control in which the receiver gas exhaust valve is opened, and the refrigerant subcooling at the radiator outlet to the target subcooling is established by performing the expansion valve subcooling control of upstream side on which the opening of the upstream side expansion valve that is provided on the upstream side of the receiver is changed, as described above. By doing so, the flow rates of the gas refrigerant and the liquid refrigerant that pass through the upstream side expansion valve and flow into the receiver are stabilized and the gas refrigerant is stably ejected outward from the receiver through the receiver gas exhaust pipe because the coolant undercooling at the radiator outlet is set to the target subcooling. For this reason, the state in which the liquid refrigerant is normally present in the receiver and the refrigerant that is sent from the receiver to the receiver is maintained.

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The downstream side expansion valve is normally maintained in the state of the liquid refrigerant.

Because of this, in this case, it is possible to perform the suction humidification control with high control capacity when R32 is used as a refrigerant.

An air conditioning apparatus according to another aspect of the first aspect is the air conditioning apparatus in which the suction humidification control of the expansion valve of

The downstream side is a control in which the opening of the downstream side expansion valve is changed so that a coolant temperature that is discharged from the compressor is set at a target discharge temperature that is equivalent to a case wherein the dryness of the refrigerant at the evaporator outlet is set to the target dryness.

In this case, it is possible to precisely perform the suction humidification control since the suction humidification control of the downstream side expansion valve is performed based on the temperature of the refrigerant that is discharged from the compressor.

An air conditioning apparatus according to another aspect of the first aspect is the air conditioning apparatus in which the subcooling control of upstream side expansion valve with respect to the upstream side expansion valve is performed and performed the downstream side expansion valve suction humidification control while a discharge temperature protection control is performed with respect to the downstream side expansion valve, so that a designated correction opening is added to a lower limit opening which is a lower control limit of the downstream side expansion valve in the case of satisfying a discharge temperature protection condition, which is determined when the temperature of the refrigerant discharged from the compressor increases to a protective discharge temperature that is greater than the target discharge temperature or when a c Status that correlates with the temperature of the refrigerant that is discharged from the compressor reaches an amount of protection status that corresponds to the protection discharge temperature.

Even by performing the downstream expansion valve suction humidification control, it is not possible to rule out concerns that the temperature of the refrigerant discharged from the compressor increases excessively due to any irregular circumstances.

Therefore, in this case, the upstream side expansion valve subcooling control is performed with respect to the upstream side expansion valve and the downstream side expansion valve suction humidification control is performed together with the completion of the discharge temperature protection control, in which the designated correction opening is added to the lower limit opening which is the lower control limit of the downstream side expansion valve with respect to the valve of downstream side expansion in the case of satisfying a discharge temperature protection condition, which is determined when the temperature of the refrigerant discharged from the compressor increases to a protective discharge temperature that is greater than the target discharge temperature or when the amount of state that is correlated with the temperature of the refrigerant that is discharged from the compress or reaches an amount of protection status corresponding to the protection discharge temperature, as described above. For this reason, it is possible that the opening of the downstream side expansion valve is increased in practice due to the performance of the discharge temperature protection control, in which the correction opening is added to the lower limit opening of the downstream side expansion valve while continuing with the upstream side expansion valve subcooling control and the downstream side expansion valve suction humidification control.

Because of this, in this case, it is possible to effectively achieve a discharge temperature protection by increasing the control capacity in a sense in which the opening is increased with respect to the downstream side expansion valve while maintaining a control state which is the upstream side expansion valve subcooling control and the downstream side expansion valve suction humidification control in order to precisely perform the suction humidification control.

An air conditioning apparatus, according to a second aspect, is the air conditioning apparatus according to the first aspect in which the correction aperture is changed according to the temperature of the refrigerant that is discharged from the compressor or the superheat of the refrigerant that is discharge from the compressor in the discharge temperature protection control.

In this case, the correction opening is changed according to the temperature of the refrigerant that is discharged from the compressor or an overheating of the refrigerant that is discharged from the compressor in the discharge temperature protection control, as described above. For example, the correction opening is increased in order to rapidly increase the opening of the downstream side expansion valve in the case where the temperature of the refrigerant that is discharged from the compressor or the superheat of the refrigerant that is discharged from the compressor they are extremely high, and the correction opening is reduced in order to gradually increase the opening of the downstream side expansion valve in the

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in which case the temperature of the refrigerant that is discharged from the compressor or the superheat of the refrigerant that is discharged from the compressor is slightly elevated.

Because of this, in this case, it is possible to further improve the discharge temperature protection control capability by appropriately changing the degree to which the opening of the downstream side expansion valve opens according to the circumstances in the control of discharge temperature protection.

Brief description of the drawings

Fig. 1 is a schematic configuration diagram of an air conditioning apparatus according to an embodiment of the present embodiment.

Figure 2 is a control block diagram of an air conditioning apparatus.

Figure 3 is a diagram illustrating details of a control configuration that includes suction humidification control during the cooling operation.

Figure 4 is a diagram illustrating details of a control configuration that includes suction humidification control during the heating operation.

Figure 5 is a flow chart of the discharge temperature protection control.

Figure 6 is a table illustrating the conditions for changing the correction opening and the correction opening valves.

Description of the realizations

An embodiment and modified examples of an air conditioning apparatus according to the present embodiment will be described below based on the diagrams. In this case, the detailed configuration of the air conditioning apparatus according to the present invention is not limited to the embodiment and the modified examples described below and modifications are possible in a range that does not depart from the essence of the invention.

(1) Configuration of the air conditioning apparatus

Figure 1 is a schematic configuration diagram of an air conditioning apparatus 1 according to an embodiment of the present embodiment.

The air conditioning apparatus 1 is an apparatus in which it is possible to perform cooling and heating in indoor spaces, such as in a building, by performing a type of steam compression refrigeration cycle. The air conditioning apparatus 1 is mainly configured by connecting an outdoor unit 2 and an indoor unit 4. In this case, the outdoor unit 2 and the indoor unit 4 are connected by a liquid refrigerant union pipe 5 and a gas refrigerant union pipe 6. That is, a refrigerant circuit 10 which is a type of vapor compression of the refrigerant circuit in the air conditioning apparatus 1 is configured by connecting the outdoor unit 2 and the indoor unit 4 via the connecting pipes 5 and 6 of refrigerant R32, which is a type of HFC refrigerant is contained in refrigerant circuit 10 as the refrigerant.

<Indoor unit>

The indoor unit 4 is installed inside and configures a part of the refrigerant circuit 10. The indoor unit 4 mainly has an indoor heat exchanger 41.

The indoor heat exchanger 41 is a heat exchanger that cools indoor air operating as a refrigerant evaporator during the cooling operation and heats indoor air operating as a radiator during the heating operation. The liquid side of the indoor heat exchanger 41 is connected to the liquid refrigerant junction pipe 5 and the gas side of the indoor heat exchanger 41 is connected to the gas refrigerant junction pipe 6.

The indoor unit 4 has an indoor fan 42 for supplying indoor air to the indoor space as a supply air after heat exchange with refrigerant in the indoor heat exchanger 41 sucking indoor air into the indoor of the indoor unit 4. That is, the indoor unit 4 has the indoor fan 42 as a fan that supplies indoor air to the indoor heat exchanger 41 as a source for heating refrigerant or a source for cooling refrigerant flowing in the indoor heat exchanger 41 . In this case, a centrifugal fan, a multi-blade fan or the like that is operated using an indoor fan motor 43 as an indoor fan 42 is used. In addition, it is possible to change the number of motor rotations

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43 indoor fan using an inverter or the like.

Various types of sensors are provided in the indoor unit 4. In detail, an indoor heat exchange liquid side temperature sensor 57 is provided in the indoor heat exchanger 41 which detects a Trrl refrigerant temperature on the liquid side of the indoor heat exchanger 41 and a sensor 58 intermediate indoor heat exchange temperature that detects a Trrm coolant temperature in an intermediate portion of the indoor heat exchanger 41. An indoor temperature sensor 59 is provided that detects a temperature Tra of indoor air that is sucked into the interior of the indoor unit 4 in the indoor unit 4.

The indoor unit 4 has an indoor side control section 44 that controls the actions of each section that configures the indoor unit 4. Then, the indoor side control section 44 has a microcomputer, a memory and the like provided to control the indoor unit 4, and is capable of transferring control signals and the like to and from a remote controller. (not shown in the diagrams) to operate the indoor unit 4 individually and to perform the transfer of control signals and the like to and from the outdoor unit 2 via a transfer line 8a.

<Outdoor unit>

The outdoor unit 2 is installed outside and configures a part of the refrigerant circuit 10. The outdoor unit 2 mainly has a compressor 21, a four-way switching valve 22, an outdoor heat exchanger 23, an outdoor heat exchange side expansion valve 24, a receiver 25, a valve 26 indoor heat exchange side expansion, a liquid side closing valve 27, a gas side closing valve 28 and a receiver gas exhaust pipe 30.

The compressor 21 is a device that compresses low pressure refrigerant so that it becomes high pressure refrigerant in the refrigeration cycle. The compressor 21 has a sealed configuration in which a positive displacement compression element (not shown in the diagrams), such as rotary type or volute type, is rotatably driven using a compressor motor 21a which It is controlled using an inverter. The suction side of the compressor 21 is connected to a suction pipe 31 and the discharge side of the compressor 21 is connected to a discharge pipe 32. The suction pipe 31 is a refrigerant pipe that connects the suction side of the compressor 21 and a first hole 22a of the four-way switching valve 22. An accumulator 29 with a low capacity is provided which is associated with the compressor 21 in the suction pipe 31. The discharge line 32 is a refrigerant line that connects the discharge side of the compressor 21 and a second orifice 22b of the four-way switching valve 22. A check valve 32a is provided, which only allows refrigerant flow from the suction side of the compressor 21 to the side of the second orifice 22b of the four-way switching valve 22, in the discharge line 32.

The four-way switching valve 22 is a switching valve for switching the direction of refrigerant flow in the refrigerant circuit 10. The four-way switching valve 22 performs the switching during the cooling operation to a cooling cycle state in which the outdoor heat exchanger 23 functions as a radiator for refrigerant that is compressed in the compressor 21 and the exchanger 41 Indoor heat functions as an evaporator for refrigerant in which heat is released in the outdoor heat exchanger 23. That is, the four-way switching valve 22 performs the switching during the cooling operation, so that the second orifice 22b and a third orifice 22c are connected and the first orifice 22a and a fourth orifice 22d are connected. Because of this, the discharge side of the compressor 21 (in this case, the discharge pipe 32) and the gas side of the outdoor heat exchanger 23 (in this case, a first gaseous refrigerant pipe 33) are connected ( see the continuous line on the four-way switching valve 22 in Figure 1). In addition, the suction side of the compressor 21 (in this case, the suction pipe 31) and the side of the gas refrigerant junction pipe 6 (in this case, a second gas refrigerant pipe 34) are connected (see continuous line on the four-way switching valve 22 in Figure 1). In addition, the four-way switching valve 22 performs the switching during the heating operation to a heating cycle state in which the outdoor heat exchanger 23 functions as an evaporator for refrigerant in which heat is released in the exchanger 41 indoor heat exchanger and indoor heat exchanger 41 functions as a radiator for refrigerant that is compressed in the compressor 21. That is, the four-way switching valve 22 performs the switching during the heating operation, so that the second hole 22b and the fourth hole 22d are joined and the first hole 22a and the third hole 22c are joined. Because of this, the discharge side of the compressor 21 (in this case, the discharge pipe 32) and the side of the gas refrigerant junction pipe 6 (in this case, the second gas refrigerant pipe 34) are connected ( see the broken line on the four-way switching valve 22 in Figure 1). In addition, the suction side of the compressor 21 (in this case, the suction pipe 31) and the gas side of the outdoor heat exchanger 23 (in this case, the first gas refrigerant pipe 33) are connected (see broken line on the four-way switching valve 22 in Figure 1). The first gaseous refrigerant pipe 33 is a refrigerant pipe connecting the third hole 22c of the four-way switching valve 22 and the gas side of the outdoor heat exchanger 23. The second gas refrigerant pipe 34 is a refrigerant pipe that connects the fourth orifice 22d of the four-way switching valve 22 and the side of the pipe 6

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gas refrigerant union.

The outdoor heat exchanger 23 is a heat exchanger that functions as a radiator for refrigerant in which the outside air is a source for cooling during the cooling operation and which functions as an evaporator for refrigerant in which outside air is a source for heating during the heating operation. The liquid side of the outdoor heat exchanger 23 is connected to a liquid refrigerant pipe 35 and the gas side of the outdoor heat exchanger 23 is connected to the first gas refrigerant pipe 33. The liquid refrigerant pipe 35 is a refrigerant pipe that connects the liquid side of the outdoor heat exchanger 23 and the pipe side 5 of the liquid refrigerant junction. The outdoor heat exchanger 23 is a heat exchanger in which flat perforated tubes are used as heat transfer tubes.

The outdoor heat exchange side expansion valve 24 is a valve that, during the cooling operation, functions as an upstream side expansion valve that reduces the pressure of high pressure refrigerant in the refrigeration cycle in the that heat is released in the outdoor heat exchanger 23 at an intermediate pressure in the refrigeration cycle. In addition, the outdoor heat exchange side expansion valve 24 is a valve that, during the heating operation, functions as a downstream side expansion valve that reduces the pressure of intermediate pressure refrigerant in the refrigeration cycle which accumulates in receiver 25 at a low pressure in the refrigeration cycle. The outdoor heat exchange side expansion valve 24 is provided in a part that is closer to the outdoor heat exchanger 23, in the liquid refrigerant pipe 35. In this case, an electric expansion valve is used as the outdoor heat exchange side expansion valve 24.

The receiver 25 is provided between the outdoor heat exchange side expansion valve 24 and the indoor heat exchange side expansion valve 26. The receiver 25 is a container in which it is possible that intermediate pressure refrigerant accumulates in the refrigeration cycle during the cooling operation and during the heating operation.

The indoor heat exchange side expansion valve 26 is a valve that, during the cooling operation, functions as a downstream side expansion valve that reduces the pressure of intermediate pressure refrigerant in the refrigeration cycle that is accumulates in the receiver 25 at low pressure in the refrigeration cycle. In addition, the indoor heat exchange side expansion valve 26 is a valve that, during the heating operation, functions as an upstream side expansion valve that reduces the high pressure refrigerant pressure in the refrigeration cycle. in which heat is released in the indoor heat exchanger 41 at an intermediate pressure in the refrigeration cycle. The indoor heat exchange side expansion valve 26 is provided in a part that is closer to the liquid side closing valve 27, in the liquid refrigerant pipe 35. In this case, an electric expansion valve is used as an indoor heat exchange side expansion valve 26.

The liquid side closing valve 27 and the gas side closing valve 28 are valves that are provided in the connection opening with external devices or pipes (in detail, the liquid refrigerant junction pipe 5 and the pipe 6 gas refrigerant junction). The liquid side shutoff valve 27 is provided in an end section of the liquid refrigerant pipe 35. The gas side shutoff valve 28 is provided at one end of the second gas refrigerant pipe 34.

The receiver gas exhaust pipe 30 is a refrigerant pipe that conducts intermediate pressure gaseous refrigerant in the refrigeration cycle that accumulates in the receiver 25 to the compressor suction pipe 31 21. The gas exhaust pipe 30 The receiver is provided to connect between an upper section of the receiver 25 and a section along the suction pipe 31. A receiver gas exhaust valve 30a, a capillary tube 30b and a check valve 30c are provided in the receiver gas exhaust pipe 30. The receiver gas exhaust valve 30a is a valve that is capable of being controlled to open and close when the cooling flow in the receiver gas exhaust pipe 30 starts and stops, and is used, in this case, an electromagnetic valve The capillary tube 30b is a mechanism that reduces pressure of the gaseous refrigerant that accumulates in the receiver 25 at low pressure in the refrigeration cycle. In this case, a capillary tube with a diameter that is narrower than the receiver gas exhaust pipe is used. The check valve 30c is a valve mechanism that only allows the flow of refrigerant from the side of the receiver 25 to the side of the suction pipe 31, and in this case a check valve is used.

The outdoor unit 2 has an outdoor fan 36 for expulsion outside after the heat exchange with refrigerant in the outdoor heat exchanger 23 by outside air that is sucked into the interior of the outdoor unit 2. That is, the outdoor unit 2 has the outdoor fan 36 as a fan that supplies outside air to the outdoor heat exchanger 23 as a source for cooling coolant or a source for heating coolant flowing in the outdoor heat exchanger 23. In this case, a helical fan or the like is used as an outdoor fan 36 which is operated using an outdoor fan motor 37. In addition, it is possible to change the number of rotations of the outdoor fan motor 37 using an inverter or the like.

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Various types of sensors are provided in the outdoor unit 2. In detail, a suction temperature sensor 51 is provided, which detects a temperature Ts of the low pressure refrigerant in the refrigeration cycle that is sucked into the compressor 21, in the suction pipe 31. In this case, the suction temperature sensor 51 is provided in a position on the downstream side of a part that joins the receiver gas exhaust pipe 30, in the suction pipe 31. A discharge temperature sensor 52, which detects a high pressure refrigerant temperature Td in the refrigeration cycle that is discharged from the compressor 21, is provided in the discharge pipe 32. An outdoor heat exchange intermediate temperature sensor 53, which detects a coolant temperature Torm in an intermediate portion of the outdoor heat exchanger 23, and an outdoor heat exchange liquid side temperature sensor 54, which detects a Torl temperature of refrigerant on the liquid side of the outdoor heat exchanger 23, are provided in the outdoor heat exchanger 23. An outdoor temperature sensor 55 that detects an outdoor air temperature Toa that is sucked into the outdoor unit 2 is provided in the outdoor unit 2. A liquid pipe temperature sensor 56, which detects a liquid pipe temperature Tlp of refrigerant in a part that is close to the inside of the indoor heat exchange side expansion valve 26, is provided in the pipe 35 of liquid refrigerant.

The outdoor unit 2 has an outdoor side control section 38 that controls the actions of each section that configures the outdoor unit 2. Then, the outer side control section 38 has a microcomputer, a memory and the like provided to perform a control of the outdoor unit 2, and is capable of transferring control signals and the like to and from the unit 4 of interior (i.e., the inner side control section 44) by the transfer line 8a.

<Coolant union pipes>

Coolant union pipes 5 and 6 are refrigerant pipes that are constructed on site when the air conditioning apparatus 1 is installed in an installation location such as a building and junction pipes having pipe diameters and lengths are used various according to the installation conditions, such as the installation location, the combination of the outdoor unit and the indoor unit, and the like.

The refrigerant circuit 10 of the air conditioning apparatus 1 is configured by connecting the outdoor unit 2, the indoor unit 4 and the refrigerant connection pipes 5 and 6, as set forth above. The air conditioning apparatus 1 performs the cooling operation by circulating refrigerant in the order of the compressor 21, the outdoor heat exchanger 23 which is the radiator, the outdoor heat exchange side expansion valve 24 which is the upstream side expansion valve, the receiver 25, the indoor heat exchange side expansion valve 26 which is the downstream side expansion valve, and the indoor heat exchanger 41 which is the evaporator. In addition, the air conditioning apparatus 1 performs the heating operation by circulating refrigerant in the order of the compressor 21, the indoor heat exchanger 41 which is the evaporator, the indoor heat exchange side expansion valve 26 which it is the upstream side expansion valve, the receiver 25, the outdoor heat exchange side expansion valve 24 which is the downstream side expansion valve, and the outdoor heat exchanger 23 which is the radiator by switching the four-way switching valve 22 to a heating cycle state. R32 is contained in refrigerant circuit 10 as refrigerant. In addition, the refrigerant circuit 10 has the receiver gas exhaust valve 30a that is capable of being controlled to open and close and the receiver gas exhaust pipe 30 is provided to conduct gaseous refrigerant that accumulates inside the receiver 25 to the suction side of the compressor 21.

<Control section>

It is possible for the air conditioning apparatus 1 to perform a check of each of the devices of the outdoor unit 2 and the indoor unit 4 using the control section 8 which is configured from the side control section 44 inner and outer side control section 38. That is, the control section 8 is configured to perform an operation check for the entire air conditioning apparatus 1 that includes the cooling operation and the heating operation described above and the like using the transfer line 8a that connects the inner side control section 44 and outer side control section 38.

The control section 8 is connected as shown in Figure 2 so that it is possible to receive detection signals of each type of the sensors 51 to 59 and the like and is connected so that it is possible to control each type of the devices, valves 21a, 22, 24, 26, 30a, 37 and 43, and the like based on these detection signals and the like.

(2) Basic actions of the air conditioning apparatus

Basic actions of the air conditioning apparatus 1 using Figure 1 will be described below. It is possible that the air conditioning apparatus 1 performs the cooling operation and the operation of

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Warming as basic actions.

<Cooling operation>

The four-way switching valve 22 is switched to the cooling cycle state (the state indicated by the continuous line in Figure 1) during the cooling operation.

Low pressure refrigerant is sucked in the refrigeration cycle in the refrigerant circuit 10 inside the compressor 21 and discharged after being compressed at high pressure in the refrigeration cycle.

The high pressure gaseous refrigerant that is discharged from the compressor 21 is sent to the outdoor heat exchanger 23 via the four-way switching valve 22.

The high pressure gaseous refrigerant that is sent to the outdoor heat exchanger 23 becomes high pressure liquid refrigerant in the outdoor heat exchanger 23 due to the release of heat when performing heat exchange with outside air that is supplied as a source for cooling using the outdoor fan 36.

The high pressure liquid refrigerant in which heat is released in the outdoor heat exchanger 23 is sent to the outdoor heat exchange side expansion valve 24. The pressure of the high pressure liquid refrigerant that is sent to the external heat exchange side expansion valve 24 is reduced to an intermediate pressure in the refrigeration cycle using the external heat exchange side expansion valve 24 . The intermediate pressure refrigerant in which the pressure is reduced using the external heat exchange side expansion valve 24 is separated into gas and liquid when sent to the receiver 25. Then, the gaseous refrigerant inside the receiver 25 is sent to the suction pipe 31 by the receiver gas exhaust pipe 30 by opening the receiver gas exhaust valve 30a. In addition, the liquid refrigerant inside the receiver 25 is sent to the indoor heat exchange side expansion valve 26.

The pressure of the intermediate pressure liquid refrigerant that is sent to the indoor heat exchange side expansion valve 26 is reduced to low pressure in the refrigeration cycle using the indoor heat exchange side expansion valve 26. The refrigerant in which the pressure is reduced using the indoor heat exchange side expansion valve 26 is sent to the indoor heat exchanger 41 via the liquid side closing valve 27 and the refrigerant union pipe 5 liquid.

The low pressure refrigerant that is sent to the indoor heat exchanger 41 is evaporated in the indoor heat exchanger 41 by performing heat exchange with indoor air that is supplied as a source for heating using the indoor fan 42. Because of this, indoor cooling is performed by cooling the indoor air and supplying it to the indoor space after this.

The low pressure refrigerant that evaporates in the indoor heat exchanger 41 is mixed with gaseous refrigerant that flows into the interior from the receiver gas exhaust pipe 30 by sending it to the suction pipe 31 via the refrigerant junction pipe 6 gas, the gas side shutoff valve 28, and the four way switching valve 22 and is suctioned back into the compressor 21.

<Heating operation>

The four-way switching valve 22 is switched to the heating cycle state (the state indicated by the dashed line in Figure 1) during the heating operation.

Low pressure refrigerant is sucked in the refrigeration cycle in the refrigerant circuit 10 inside the compressor 21 and discharged after being compressed at high pressure in the refrigeration cycle.

The high-pressure gaseous refrigerant that is discharged from the compressor 21 is sent to the indoor heat exchanger 41 via the four-way switching valve 22, the gas side shut-off valve 28 and the gas coolant junction pipe 6 .

The high pressure gaseous refrigerant that is sent to the indoor heat exchanger 41 becomes high pressure liquid refrigerant in the indoor heat exchanger 41 due to the release of heat when performing heat exchange with indoor air that is supplied as a source for cooling using the indoor fan 42. Because of this, indoor heating is performed by heating the indoor air and supplying it to the indoor space after this.

The high pressure liquid refrigerant in which heat is released in the indoor heat exchanger 41 is sent to the indoor heat exchange side expansion valve 26 via the liquid refrigerant junction pipe 5 and the valve 27 liquid side closure.

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The pressure of the high pressure liquid refrigerant that is sent to the indoor heat exchange side expansion valve 26 is reduced to an intermediate pressure in the refrigeration cycle using the indoor heat exchange side expansion valve 26 . The intermediate pressure refrigerant in which the pressure is reduced using the indoor heat exchange side expansion valve 26 is separated into gas and liquid when sent to the receiver 25. Then, the gaseous refrigerant inside the receiver 25 is sent to the suction pipe 31 by the receiver gas exhaust pipe 30 by opening the receiver gas exhaust valve 30a. In addition, the liquid refrigerant inside the receiver 25 is sent to the external heat exchange side expansion valve 24. The pressure of the intermediate-pressure liquid refrigerant that is sent to the outdoor heat exchange side expansion valve 24 is reduced to low pressure in the refrigeration cycle using the outdoor heat exchange side expansion valve 24. The low pressure refrigerant in which the pressure is reduced using the outdoor heat exchange side expansion valve 24 is sent to the outdoor heat exchanger 23.

The low pressure liquid refrigerant that is sent to the outdoor heat exchanger 23 evaporates in the outdoor heat exchanger 23 upon heat exchange with outside air that is supplied as a source for heating using the outdoor fan 36.

The low-pressure refrigerant that evaporates in the outdoor heat exchanger 23 is mixed with gaseous refrigerant that flows into the interior from the receiver gas exhaust pipe 30 when sent to the suction pipe 31 by means of the switching valve 22 four ways and is sucked back into the compressor 21.

(3) Functional control that includes suction humidification control

In this case, since R32 is used as a refrigerant, it is necessary to carry out a suction humidification control so that the refrigerant at the outlet of an evaporator (the indoor heat exchanger 41 during the cooling operation and the heat exchanger 23 outside heat during the heating operation) is in the designated humidification state during the cooling operation and during the heating operation described above taking into account that it is easy to increase the temperature Td of the refrigerant that is discharged from the compressor 21. In this case, there is concern that an increase in the temperature Td of the refrigerant that is discharged from the compressor 21 is generated when the compressor 21 sucks refrigerant in which the dryness is greater than the designated humidification state and compression of liquid when the compressor 21 sucks refrigerant in which the dryness is less than the state d and designated humidification. For this reason, a high control capacity is required with respect to the control of suction humidification from the point of view of guaranteeing the reliability of the compressor 21. Furthermore, in this case, the concern that liquid compression is generated is high that a configuration is adopted in which an accumulator with a large capacity that has a gas and liquid separation function is not provided, so that it is possible for the refrigerant to be sucked into the compressor 21 in a humidifying state. For this reason, it is necessary that the control capacity of the suction humidification control be further improved so that the compressor 21 does not suck refrigerant in which the dryness is less than the designated humidification state.

In this way, a high control capacity is required in the control of suction humidification from the point of view of guaranteeing the reliability of the compressor 21, being necessary to perform a suction humidification control in the case where R32 is used as refrigerant in the air conditioning apparatus 1 having the refrigerant circuit 10 in which the expansion valves 24 and 26 are provided on the upstream side and the downstream side of the receiver 25 and gaseous refrigerant is injected from the receiver 25 inside the compressor 21.

Therefore, in this case, an operation control is performed that includes the suction humidification control as described above during the cooling operation and during the heating operation.

Next, the operation control that includes the suction humidification control during the cooling operation and during the heating operation using Figures 1 to 4 will be described. In this case, Figure 3 is a diagram illustrating details of a configuration of control that includes the control of suction humidification during the cooling operation. Figure 4 is a diagram illustrating details of a control configuration that includes the suction humidification control during the heating operation.

<Operation control that includes suction humidification control during cooling operation>

The operation control that includes the suction humidification control during the cooling operation will first be described.

In this case, it is preferable to control a device that is capable of directly controlling the flow rate of refrigerant flowing into the interior of the indoor heat exchanger 41 which is the evaporator in the suction humidification control since the circuit 10 is refrigerant in which the expansion valves 24 and 26 are provided on the upstream side and the downstream side of the receiver 25 and gaseous refrigerant is injected from the receiver 25 into the compressor 21.

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Therefore, in this case, the refrigerant is in a humidifying state and a dryness Xs of the refrigerant is established at an objective dryness Xst at the outlet of the indoor heat exchanger 41 by performing the suction humidification control of the expansion valve downstream side where the opening of the indoor heat exchange side expansion valve 26, which is the downstream side expansion valve provided on the downstream side of the receiver 25, is changed using a section 81 suction humidification control of the downstream side expansion valve of control section 8.

In this case, as a suction humidification control of the downstream side expansion valve, a control is adopted in which the opening of the indoor heat exchange side expansion valve 26 is changed, so that the temperature Td of the refrigerant that is discharged from the compressor 21 is set at a target discharge temperature Tdt which is equivalent to a case in which the dryness Xs is set to the objective dryness Xst at the outlet of the indoor heat exchanger 41. In this case, it is preferable that the target dryness Xst is controlled to be in the range of 0.65 to 0.85 from the point of view of suppressing an excessive increase in the temperature Td of the refrigerant that is discharged from the compressor 21 and suppress the generation of liquid compression. However, it is not possible to directly detect the dryness Xs of refrigerant at the outlet of the indoor heat exchanger 41. Therefore, in this case, the target discharge temperature Tdt which is equivalent to a case in which the dryness Xs is the target dryness Xst (in a range of 0.65 to 085) using the temperature Td of the refrigerant that is discharged from the compressor 21 instead of the dryness Xs, and the opening of the indoor heat exchange side expansion valve 26 is changed, so that the temperature Td of the refrigerant discharged from the compressor 21 is the temperature of Tdt target download. That is, it is determined that the dryness Xs is greater than the objective dryness Xst in the case where the temperature Td is greater than the target discharge temperature Tdt and the change is made so that the opening of the valve 26 is reduced of indoor heat exchange side expansion. In addition, it is determined that the dryness Xs is less than the objective dryness Xst in the case where the temperature Td is lower than the target discharge temperature Tdt and the change is made so that the opening of the valve 26 is increased. Indoor heat exchange side expansion.

However, at this point, it is preferable that the refrigerant sent from the receiver 25 to the indoor heat exchange side expansion valve 26 is normally maintained in the state of liquid refrigerant so that the control capacity of the indoor heat exchange side expansion valve 26 is suitable. Then, it is necessary that the flow rates of the gaseous refrigerant and the liquid refrigerant flowing into the receiver 25 are stabilized, so that the gaseous refrigerant does not flow from the receiver 25 into the expansion valve 26 of the exchange side exchange indoor heat, and so that the liquid refrigerant does not return from the receiver gas exhaust pipe 30 to the suction side of the compressor 21 so that the refrigerant that is sent from the receiver 25 to the side-side expansion valve 26 Indoor heat exchange is normally maintained in the state of liquid refrigerant.

Therefore, in this case, when performing the suction humidification control of the downstream expansion valve, gaseous refrigerant is conducted from the receiver 25 to the suction side of the compressor 21 via the gas exhaust pipe 30 receiver that is provided in the receiver 25 performing the gas exhaust control in which the receiver gas exhaust valve 30a is opened using a gas exhaust control section 83 of the control section 8, and the subcooling SC of refrigerant at the outlet of the outdoor heat exchanger 23 which is a radiator is set to an objective subcooling SCt by performing the subcooling control of the upstream side expansion valve in which the opening of the expansion valve 24 is changed outside heat exchange side, which is the upstream side expansion valve provided on the upstream side of the receiver 25, using a section 82 of c Undercooling control of the upstream side expansion valve of the control section 8.

In this case, the refrigerant subcooling SC at the outlet of the outdoor heat exchanger 23 is obtained by subtracting the Torl temperature from the refrigerant that is detected using the outdoor heat exchange liquid side temperature sensor 54 at the Torm temperature of the refrigerant that is detected using the intermediate heat exchange intermediate temperature sensor 53. The objective subcooling SCt is set to a value to the extent that it is possible to guarantee an amount of liquid refrigerant after the refrigerant pressure is reduced to an intermediate pressure in the refrigeration cycle using the exchange side expansion valve 24 of outdoor heat. Then, a change is made so that the opening of the outdoor heat exchange side expansion valve 24 is increased in the case where the subcooling SC is greater than the objective subcooling SCt. In addition, a change is made, so that the opening of the outdoor heat exchange side expansion valve 24 is reduced in the case where the subcooling SC is smaller than the objective subcooling SCt.

By doing this, the flow rates of the gaseous refrigerant and the liquid refrigerant that pass through the external heat exchange side expansion valve 24 and which flow into the receiver 25 are stabilized and the gaseous refrigerant is expelled to the stably outside from the receiver 25 via the receiver gas exhaust pipe 30 because the coolant subcooling SC is established at the outlet of the outdoor heat exchanger 23 to the target subcooling SCt. For this reason, a

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state in which there is normally liquid refrigerant in the receiver 25 and the refrigerant that is sent from the receiver 25 to the indoor heat exchange side expansion valve 26 in the liquid refrigerant state is normally maintained.

Because of this, in this case, it is possible to perform the suction humidification control with high control capacity when R32 is used as a refrigerant.

In addition, in this case, it is possible to precisely carry out the suction humidification control since the suction humidification control of the downstream side expansion valve is performed based on the temperature Td of the refrigerant discharged from the compressor twenty-one.

In addition, in this case, the compressor capacity control is performed so that the number of rotations of the compressor 21 is changed so that a low pressure Pe in the refrigeration cycle of the refrigerant circuit 10 is set to a low target pressure Weigh using a compressor capacity control section 84 of control section 8.

In this case, the low pressure Pe in the refrigeration cycle is a value at which the Trrm temperature of the refrigerant, which is equivalent to the evaporation temperature of the refrigerant in the indoor heat exchanger 41 that is detected using the sensor 58 Intermediate indoor heat exchange temperature, it becomes a saturation pressure. The low target pressure Pes is set to a value in the degree to which it is possible to obtain the cooling capacities that are required during the cooling operation. Then, the change is made, so that the number of rotations of the compressor 21 is increased in the case where the low pressure Pe is greater than the low target pressure Pes. In addition, the change is made so that the number of rotations of the compressor 21 is reduced in the case where the low pressure Pe is less than the low target pressure Pes.

Because of this, it is possible to stabilize the subcooling SC and the dryness Xs and stably perform the suction humidification control of the downstream side expansion valve, the gas leakage control and the subcooling control of the flow valve. upstream expansion described above, since it is possible to stabilize the low pressure in the refrigeration cycle and the low pressure and high pressure in the refrigeration cycle of the refrigerant circuit 10.

<Operation control that includes suction humidification control during heating operation>

Next, the operation control that includes the suction humidification control during the heating operation will be described.

The suction humidification control of the downstream side expansion valve is also performed using the suction humidification control section 81 of the downstream side expansion valve of the control section 8 during the heating operation of the same way as during the cooling operation. In detail, the refrigerant is in a humidifying state and the dryness Xs of the refrigerant is set to the target dryness Xst at the outlet of the outdoor heat exchanger 23 which is the evaporator by performing the suction humidification control of the expansion valve downstream side where the opening of the outdoor heat exchange side expansion valve 24 is changed, which is the downstream side expansion valve provided on the downstream side of the receiver 25.

In addition, by performing the suction humidification control of the downstream side expansion valve, gaseous refrigerant is conducted from the receiver 25 to the suction side of the compressor 21 via the receiver gas exhaust pipe 30 provided in the receiver 25 performing the gas exhaust control in which the receiver gas exhaust valve 30a is opened using the gas exhaust control section 83 of the control section 8, and the coolant subcooling SC at the outlet of the outdoor heat exchanger 41, which is the radiator, is set to the objective subcooling SCt by performing the subcooling control of the upstream side expansion valve in which the opening of the exchange side expansion valve 26 is changed of indoor heat, which is the upstream side expansion valve provided on the upstream side of receiver 25, using subcool control section 82 Upstream side valve expansion of the control section 8 during the heating operation in the same manner as during the cooling operation. In this case, the coolant subcooling SC at the outlet of the indoor heat exchanger 41 is obtained by subtracting the Trrl temperature of the refrigerant that is detected using the indoor heat exchange liquid side temperature sensor 57 at the Trrm temperature of the refrigerant that is detected using the indoor heat exchange intermediate temperature sensor 58.

In doing so, the flow rates of the gas refrigerant and the liquid refrigerant that pass through the indoor heat exchange side expansion valve 26 and flow into the receiver 25 are stabilized and the gas refrigerant is expelled to the outside stably from the receiver 25 via the receiver gas exhaust line 30 because the coolant subcooling SC is established at the outlet of the indoor heat exchanger 41 to the target subcooling SCt in the same manner as during the operation

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Cooling. For this reason, a state is maintained in which there is normally liquid refrigerant in the receiver 25 and the refrigerant that is sent from the receiver 25 to the external heat exchange side expansion valve 24 is normally maintained in the state of liquid refrigerant

Because of this, it is also possible to perform the suction humidification control with high control capacity when R32 is used as a refrigerant during the heating operation.

In addition, the compressor capacity control is also performed during the heating operation so that the number of rotations of the compressor 21 is changed so that a high pressure Pc in the refrigeration cycle of the refrigerant circuit 10 is set to a high target pressure Pcs using compressor capacity control section 84 of control section 8.

In this case, the high pressure Pc in the refrigeration cycle is a value at which the refrigerant Trrm temperature, which is equivalent to the refrigerant condensation temperature in the indoor heat exchanger 41 that is detected using the sensor 58 Intermediate indoor heat exchange temperature, it becomes a saturation pressure. The high target pressure Pcs is set to a value to the extent that it is possible to obtain the heating capacities that are required during the heating operation. Then, the change is made so that the number of rotations of the compressor 21 is reduced in the case where the high pressure Pc is greater than the high target pressure Pcs. In addition, the change is made so that the number of rotations of the compressor 21 is increased in the case where the high pressure Pc is less than the high target pressure Pcs.

Because of this, it is possible to stabilize the subcooling SC and the dryness Xs and stably perform the suction humidification control of the downstream side expansion valve, the gas exhaust control, and the valve subcooling control upstream side expansion described above, since it is possible to stabilize the high pressure in the refrigeration cycle and the low pressure and high pressure in the refrigeration cycle of the refrigerant circuit 10.

(4) Modified example 1

Even if the operation control that includes the suction humidification control of the downstream dellated expansion valve described above is performed, it is not possible to stop worrying that the temperature Td of the refrigerant that is discharged from the compressor 21 is excessively increased due to to any irregular circumstances.

Therefore, in this case, the upstream side expansion valve subcooling control is performed in the same manner as described above with respect to the upstream side expansion valves 24 and 26 and the humidification control of downstream side expansion valve suction is performed together with the completion of the discharge temperature protection control, in which a correction opening designated AMVm is added to a lower limit opening MVm, which is the lower control limit of the downstream expansion valves 26 and 24 with respect to the downstream expansion valves 26 and 24 in the case of satisfying a discharge temperature protection condition, which is determined when the refrigerant temperature Td that discharged from the compressor 21 increases at a protective discharge temperature Tdi that is greater than the target discharge temperature Tdt or when a amount of state that is correlated with the temperature Td of the refrigerant that is discharged from the compressor 21 reaches an amount of protection status corresponding to the protection discharge temperature Tdi.

Next, the operation control of the discharge temperature protection control using figures 1 to 5 will be described. In this case, Figure 5 is a flow chart of the discharge temperature protection control. The discharge temperature protection control described below is performed by the downstream side expansion valve suction humidification control section 81 of the control section 8.

During operation control which includes the upstream side expansion valve subcooling control and the downstream side expansion valve suction humidification control, section 81 side expansion valve suction humidification control downstream first determines whether the discharge temperature protection condition is satisfied or not in step ST1. In this case, the most direct indicator that is an indicator of whether the discharge temperature protection condition is satisfied or not is whether the temperature Td of the refrigerant discharged from the compressor 21 increases or not at the protective discharge temperature Tdi which is higher than the target discharge temperature Tdt. However, the indicator of whether or not the discharge temperature protection condition is satisfied is not limited to this, and it can be determined whether or not the discharge temperature protection condition is satisfied depending on whether the overheating of discharge TdSH, the low pressure Pe or the suction superheat TsSH, which are state quantities that are correlated with the temperature Td of the refrigerant that is discharged from the compressor 21, reach or not the overheating of protection discharge TdSHi, the low protection pressure Pei or TsSHi suction protection overheating, which are amounts of protection status corresponding to the protection discharge temperature Tdi. For this reason, in this case, the determination of whether or not the discharge temperature protection condition is satisfied is determined depending on whether any of the four of the quantities

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of state Td, TdSH, Pe and TsSH, respectively, reach or not the amounts of protection status. In this case, the superheat TdSH of the refrigerant that is discharged from the compressor 21 is obtained by subtracting the Torm temperature of the refrigerant that is detected using the intermediate heat exchange intermediate temperature sensor 53 to the temperature Td of the refrigerant that is discharged from the compressor 21 during the cooling operation and is obtained by subtracting the Trrm temperature from the refrigerant that is detected using the intermediate temperature sensor 58 of the indoor heat exchange side to the temperature Td of the refrigerant that is discharged from the compressor 21 during the heating operation The TsSH superheat of the refrigerant that is sucked into the compressor 21 is obtained by subtracting the Trrm temperature from the refrigerant that is detected using the indoor heat exchange intermediate temperature sensor 58 to the temperature Ts of the refrigerant that is sucked into the compressor 21 during the cooling operation and is obtained by subtracting the Torm temperature from the refrigerant that is detected using the intermediate heat exchange intermediate temperature sensor 53 to the temperature Ts of the refrigerant that is sucked into the compressor 21 during the heating operation .

Next, when it is determined that the discharge temperature protection condition is satisfied in step ST1, the downstream side expansion valve suction humidification control section 81 of the control section 8 performs the protection control of discharge temperature at which the designated AMVm correction opening is added to the lower limit opening MVm, which is the lower control limit of the downstream side expansion valves 26 and 24 in step ST2. Because of this, it is possible that the opening of the downstream side expansion valves 26 and 24 in practice may be increased while continuing the operation control that includes the upstream side expansion valve subcooling control and the suction humidification control of downstream side expansion valve. The discharge temperature protection control is performed in step ST2 until a discharge temperature resolution condition in step ST3 is satisfied. In this case, it is determined whether or not the discharge temperature resolution condition is satisfied depending on whether any of the four of the status amounts Td, TdSH, Pe and TsSH respectively reach or not the resolution status amounts of the same way as the discharge temperature protection condition in step ST1. In detail, it is determined whether or not the discharge temperature resolution condition is satisfied depending on whether the temperature Td of the refrigerant discharged from the compressor 21 is reduced or not at a discharge temperature of resolution Tdo that is less than the Tdi protection discharge temperature and if the TdSH discharge superheat, the low Pe pressure or the TsSH suction superheat reach or not the TdSHo resolution discharge superheat, the Peo resolution low pressure or the TsSHo resolution suction superheat which are the resolution status amounts that correspond to the resolution download temperature Tdo. That is, after the discharge temperature protection condition is satisfied in step ST1, the downstream side expansion valve suction humidification control section 81 of the control section 8 repeats the protection control of discharge temperature at which the designated AMVm correction opening is added to the lower limit opening MVm which is the lower control limit of downstream side expansion valves 26 and 24 while continuing with the operation control that includes the upstream side expansion valve subcooling control and the downstream side expansion valve suction humidification control until the discharge temperature resolution condition in step ST3 is satisfied. In this case, the lower control limit of the downstream side expansion valves 26 and 24 implies a lower control limit in the downstream side expansion valve suction humidification control since the valves 26 and 24 of downstream side expansion perform humidification control of downstream side expansion valve suction, as described above. For this reason, the designated AMVm correction opening is added to a lower limit opening MVm0 which is an initial value of the lower control limit in the downstream side expansion valve suction humidification control in the case where it is determined that the discharge temperature protection condition is initially satisfied in the process of step ST1, and the AMVm correction opening is added to the lower limit opening MVm in which the AMVm correction opening is added.

Because of this, in this case, it is possible to effectively achieve the discharge temperature protection by increasing the control capacity in a sense in which the opening is increased with respect to the downstream side expansion valves 26 and 24 while a control state is maintained which is the operation control which includes the upstream side expansion valve subcooling control and the downstream side expansion valve suction humidification control in order to accurately perform the suction humidification control.

Then, in the case where it is determined that the discharge temperature resolution condition is satisfied in step ST3, the downstream side expansion valve suction humidification control section 81 of the control section 8 returns back to the process of determining whether or not the discharge temperature protection condition of step ST1 is satisfied after the opening of the lower limit MVm which is the lower control limit of the side expansion valves 26 and 24 downstream, return to the opening of the lower limit MVm0 which is the initial value of the lower control limit in the suction humidification control of the downstream side expansion valve. Because of this, the downstream side expansion valve suction humidification control is resolved.

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(5) Modified example 2

The suction humidification control section 81 of the downstream side expansion valve of the control section 8 performs a control in which the AMVm correction opening is added to the lower limit opening MVm of the valves 26 and 24 of downstream side expansion advancing to the discharge temperature protection control in step ST2 by determining whether or not the discharge temperature protection condition in step ST1 is satisfied in the modified example 1 described above. At this point, the correction aperture AMVm may be a certain opening but may be changed according to the temperature Td of the refrigerant that is discharged from the compressor 21 or the superheat TdSH of the refrigerant that is discharged from the compressor 21.

For example, as shown in Figure 6, the AMVm correction opening is set to a first AMVmH correction opening so that the opening of the downstream side expansion valves 26 and 24 is rapidly increased in the case where that the temperature Td of the refrigerant that is discharged from the compressor 21

0 the superheat TdSH of the refrigerant discharged from the compressor 21 is extremely high (in the case where a first protection discharge temperature TdH or a first protection discharge superheat TdSHH is exceeded). In addition, the correction opening is set to a second AMVmM correction opening that is smaller than the first AMVmH correction opening so that the opening of the downstream side expansion valves 26 and 24 is gradually increased in the case where that the temperature Td of the refrigerant discharged from the compressor 21 or the superheat TdSH of the refrigerant discharged from the compressor 21 is slightly elevated (in the case where a second protection discharge temperature TdM or a second is exceeded TdSHM protection discharge overheating that are lower than the first TdH protection discharge temperature and the first TdSHH protection discharge superheat). In addition, the correction opening is set to a third AMVmL correction opening that is less than the second AMVmM correction opening in the case where the temperature Td of the refrigerant discharged from the compressor 21 or the superheat TdSH of the refrigerant that Discharged from the compressor 21 are low (in the case where a third protection discharge temperature TdL or a third protection discharge superheat TdSHL is not exceeded which are lower than the second protection discharge temperature TdM and the second overheat protection discharge TdSHM). In this case, the third protection discharge temperature TdL and the third protection discharge superheat TdSHL are greater than the resolution discharge temperature Tdo and the resolution discharge superheat TdSHo.

Because of this, in this case, it is possible to further improve the discharge temperature protection control capability by appropriately changing the degree to which the opening of the downstream side expansion valves 26 and 24 is changed according to the circumstances. in the discharge temperature protection control.

In this case, the correction aperture AMVm is changed according to the temperature Td of the refrigerant that is discharged from the compressor 21 or the superheat TdSH of the refrigerant that is discharged from the compressor 21 but is not limited to this and can be changed according to the low pressure Pe and TsSH suction overheating.

Industrial applicability

It is possible to widely apply the present invention with respect to air conditioning apparatus having a refrigerant circuit that is configured by connecting a compressor, a radiator, an upstream side expansion valve, a receiver, a water side expansion valve below and an evaporator and in which it is possible to circulate refrigerant in the order of the compressor, the radiator, the upstream side expansion valve, the receiver, the downstream side expansion valve and the evaporator.

List of reference symbols

1 AIR CONDITIONING DEVICE 10 REFRIGERANT CIRCUIT

21 COMPRESSOR

23 EXTERIOR HEAT EXCHANGER (RADIATOR, EVAPORATOR)

24 EXTERNAL HEAT EXCHANGE SIDE VALVE EXTERNAL SIDE (WATER SIDE EXPANSION VALVE UP, WATER SIDE EXPANSION VALVE DOWN)

26 INTERIOR HEAT EXCHANGE SIDE VALVE EXPANSION VALVE (

WATER SIDE EXPANSION BELOW, WATER SIDE EXPANSION VALVE UP) 25 RECEIVER

5 30 RECEIVER GAS EXHAUST PIPE

30th RECEPTOR GAS EXHAUST VALVE

41 INTERIOR HEAT EXCHANGER (EVAPORATOR, RADIATOR)

10

Reference List

Patent Bibliography

15 PTL 1: Japanese Patent Application Publication Unexamined No. H10-132393

PTL 2: Japanese Patent Application Publication Without Examining No. 2001-194015

PTL 3: Japanese Patent Application Publication Without Examining No. 2001-241780

twenty

PTL 4: European Patent Application Publication No. EP 0 685592 A2

Claims (1)

5 10 fifteen twenty 25 30 35 40 Four. Five fifty 55 60 65 Air conditioning apparatus (1) comprising: a refrigerant circuit (10) that is configured by connecting a compressor (21), a radiator (23, 41), an upstream side expansion valve (24, 26), a receiver (25), a valve (26, 24) downstream expansion and an evaporator (41, 23), and in which it is possible to circulate refrigerant in the order of the compressor, the radiator, the upstream side expansion valve, the receiver, the valve downstream side expansion and evaporator, further comprising a control section (8) comprising a downstream side expansion valve suction humidification control section (81) configured to perform a downstream side expansion valve suction humidification control, an upstream side expansion valve subcooling control section (82) configured to perform an upstream side expansion valve subcooling control and a gas exhaust control section (83) configured to perform a gas exhaust control, in which R32 is contained in the refrigerant circuit as the refrigerant, The refrigerant circuit is provided with a receiver gas exhaust pipe (30) that is for conducting gaseous refrigerant that accumulates inside the receiver to the suction side of the compressor and has an exhaust valve (30a) of receiver gas that is capable of being controlled to open and close, the gas exhaust control (83) is configured to be carried out so that the gaseous refrigerant is conducted from the receiver (25) to the suction side of the compressor (21) by the receiver gas exhaust pipe (30) opening the receiver gas exhaust valve (30a), the upstream side expansion valve subcooling control (82) is configured to be performed so that an opening of the upstream side expansion valve (24, 26) is changed so that a coolant subcooling is set to objective subcooling at the radiator outlet, and the downstream side expansion valve suction humidification control (81) is configured to be performed so that an opening of the downstream side expansion valve (24, 26) is changed so that the refrigerant is in a humidification state and a dryness is established at an objective dryness at the evaporator outlet, characterized in that The downstream side expansion valve suction humidification control (81) is a control in which the opening of the downstream side expansion valve (24, 26) is changed so that a coolant temperature is set which is discharged from the compressor (21) at an objective discharge temperature that is equivalent to a case in which the dryness of the refrigerant at the evaporator outlet (41, 23) is set to the objective dryness, the upstream side expansion valve subcooling control (82) is configured to be performed with respect to the upstream side expansion valve (24, 26) and the expansion expansion valve suction humidification control (81) downstream side is configured to be performed while a discharge temperature protection control is configured to be performed with respect to the downstream side expansion valve (26, 24) so that a designated correction opening is added to an opening lower limit which is a lower control limit of the downstream side expansion valve (24,26) in the case of satisfying a discharge temperature protection condition, which is determined when the refrigerant temperature discharged from the compressor (21) increases at a protective discharge temperature that is greater than the target discharge temperature or when the amount of state that is correlated with the temperature of the refrigerant that is discharged from the compressor (21) reaches an amount of protection status corresponding to the protection discharge temperature. Air conditioning apparatus (1) according to claim 1, wherein the correction aperture is changed according to the coolant temperature that is discharged from the compressor (21) or an overheating of the refrigerant that is discharged from the compressor in the discharge temperature protection control.